For 'Jason Bourne,' Matt Damon trained to the point of exhaustion

The trailer for the new Jason Bourne presents many questions about the titular action hero, but it makes one thing very clear: Star Matt Damon is ripped.

Damon, now 45, shows off a decidedly more muscular physique in this action film than he had in the last Bourne movie, almost a decade ago. In Jason Bourne, he's shown shirtless and fist-fighting as his gargantuan biceps bulge.

He looks strong, but he also looks spent.

"I wanted him to be in an exhausted state," says trainer Jason Walsh, who worked with Damon on JasonBourne and first trained the actor for The Informant. "(The filmmakers) wanted him to be very raw, a guy that is conflicted and (experiencing) mental turmoil. They wanted that to come across especially in that first fight scene when he's doing bare-knuckle brawl fights."

So, Walsh had to seriously tire Damon out. After training the actor on Oscar-nominated film The Martian and then China-set movie TheGreat Wall (out next year) with only a few weeks in between shoots, the two went to work on making Damon a formidable action hero.

"Two weeks from the end of Great Wall, we started to do more conditioning, lots more VersaClimber, which is a climbing machine. We went on long runs, like on these humongous hills in the Canary Islands. We did a couple days of heavy lifting and metabolic training."

The workout lasted for about an hour-and-a-half a day, five days a week, for about six months. Damon also worked with a boxing coach and a chef to get in shape for the film.

"On his face, you'll see the exhaustion" in the movie, says Walsh, who trained out alongside Damon. "I knew how he was feeling, and I really felt it. We just looked at each other, and we’re like, 'this sucks'," he says. "We'd just complete a run or something, look at each other (and say), 'That was horrible, are you tired?' 'Im tired.'"

Walsh calls Damon "the best gym buddy" who's always the first one in the gym, ready to workout with a smile. "You wouldn’t believe how strong Matt is. When you’re strong, you’re resilient and almost impervious to injury," says Walsh.

"I can’t say enough about the guy. He's the real deal."

Walsh teaches group classes on the VersaClimber in a gym he founded, called Rise Nation. And let us just tell you: His class is challenging! We took his 30-minute, full-body class in West Hollywood, where we climbed (moved our arms and hands up and down) to the beat of club music with dynamic lighting. By the end, we felt wiped, extremely sweaty and capable of taking on anything (because really nothing could be as tiring as that). Walsh's studio is opening a second location in New York by January 2017.